Spatial Heterogeneity of Light and Woody Seedling Regeneration in Tropical Wet Forests

Nicotra, Adrienne B.; Chazdon, Robin L.; Iriarte, Silvia

doi:10.2307/176668

Cited by 309 publications

(264 citation statements)

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“…Essa limitação no recrutamento de plântulas pode ser devido a um pequeno número de sementes produzidas e/ou dispersas, ou mesmo a processos pós-dispersão afetando o sucesso de estabelecimento de plântulas. Em ambientes florestais tropicais, a abundância e riqueza de plântulas e jovens de espécies arbóreas é influenciada principalmente pela disponibilidade de luz, pelo padrão de produção e dispersão de sementes, e pela ação de predadores de sementes e de plântulas, além da incidência de danos físicos (Brokaw 1985, Clark & Clark 1985, 1989, Augspurger & Kitajima 1992, Nicotra et al 1999, Denslow & Guzman 2000, Scariot 2000. Segundo Harms et al (2000), o recrutamento de espécies arbóreas e arbustivas tropicais é fortemente dependente da densidade de sementes, o que pode afetar substancialmente a dinâmica e composição da comunidade.…”

Section: Introductionunclassified

A regeneração florestal em áreas de floresta secundária na Reserva Florestal do Morro Grande, Cotia, SP

Alves

Metzger

2006

Biota Neotrop.

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Notwithstanding its complexity, a more integrated knowledge of the regeneration process in tropical forests subject to natural as well as human disturbance is necessary. Given the great extent of secondary forests in the Neotropics, an important topic to be considered is the potential of secondary forest patches to preserve the biological diversity of old-growth, less disturbed forests. The main objective of this study was to evaluate tree seedling community structure and its potential as source of regeneration in areas of secondary forest within the Morro Grande Forest Reserve (RFMG), one of the most important areas of Atlantic Rain Forest on the Atlantic Plateau. The structure and composition of the tree seedling community was sampled in 1 m 2 plots randomly placed in three areas of secondary forest. We recognized 106 species among 742 sampled tree seedlings, distributed in 35 families and 69 genera. The richest families (Myrtaceae, Fabaceae, Rubiaceae and Lauraceae) represented 47% of the species total, and the five more abundant species were Myrcia fallax, Ocotea dispersa, Psychotria vellosiana, Psychotria suterella, and Matayba elaeagnoides. Woody species regeneration was predominantly composed of zoochoric and shade tolerant species, characteristics of more advanced stages of Atlantic Rain Forest succession. Tree seedling community did not vary in abundance and size structure, but species composition and richness varied significantly among areas. Our results suggest that woody regeneration in secondary forest areas of the RFMG has a high potential of maintaining tree biological diversity of oldgrowth forests and, consequently, contributing to forest restoration at the regional scale. Spatial heterogeneity in floristic composition and species richness of the seed rain, as well as of the tree seedling community in secondary forest patches, represent important components that influence the sucessional process and the maintenance of species diversity, therefore acting as sources of recruitment of new individuals and species. Apesar de sua complexidade, é necessário um conhecimento mais sintético sobre o processo de regeneração em florestas tropicais sujeitas a diferentes regimes de perturbação, tanto natural como antrópico. Dada a grande extensão de florestas secundárias na região Neotropical, um importante tópico a ser abordado é o potencial dessas manchas de floresta na conservação da diversidade biológica do componente arbóreo típico de manchas de floresta mais antiga, menos perturbada. O objetivo principal deste estudo foi avaliar a estrutura da comunidade de plântulas de espécies arbóreas e arbustivas e seu potencial como fonte de regeneração em áreas de floresta secundária na Reserva Florestal do Morro Grande (RFMG), uma das porções mais significativas de Mata Atlântica no Planalto Atlântico. A estrutura e composição da comunidade foram amostradas através de parcelas de 1 m 2 alocadas em três áreas de floresta secundária localizadas no interior da RFMG. Foram identificadas 106 espécies dentre as 742 plân...

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Section: Introductionunclassified

A regeneração florestal em áreas de floresta secundária na Reserva Florestal do Morro Grande, Cotia, SP

Alves

Metzger

2006

Biota Neotrop.

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“…An examination of Q i /Q o frequency distribution in various Costa Rican wet forests (Nicotra et al, 1999) showed that in old-growth stands, 33-50% of the micro-sites received <1% of full sunlight compared to 11-36% of those in secondary growth stands. In a tropical deciduous forest in Mexico, Maass et al (1995) observed a minimum Q i /Q o during the wet season of approximately 0.05, whereas during the dry season Q i /Q o values were higher than 0.2.…”

Section: Discussionmentioning

confidence: 99%

“…Studies on tropical forests demonstrated that light conditions on the forest floor play an important role in the growth and survival of seedlings (Montgomery and Chazdon, 2002), species diversity (Schnitzer and Carson, 2001) and on seedling abundance and distribution (Nicotra et al, 1999). In situ studies on seedling growth and survival in Cerrado species are scarce.…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal variability of canopy cover and understory light in a Cerrado of Southern Brazil

Lemos-Filho

Barros²,

Dantas³

et al. 2010

Braz. J. Biol.

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Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI) values in the rainy season varied from 0.9 to 4.83, with 40% of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53% of the values oscilating from 2.0 to 3.0. Understory light (Q i ) and the Lambert-Beer ratio (Q i /Q o ) were taken around noon on sunny days (between 11:00 AM and 1:00 PM). They were also statistically different (p < 0.01) between the dry and wet seasons, with 72% of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD) values lower than 250 μmol.m -2 /s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 μmol.m -2 /s , thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50% of their photosynthetic capacity in the wet season. In contrast during the dry season, Q i /Q o values of 0.8 to 1.0 were observed in more than 50% of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.Keywords: leaf area index, Lambert-Beer ratio, photosynthesis, seedling growth, tropical savanna.Variabilidade espacial e temporal da cobertura do dossel e da luz no sub-bosque em uma área de Cerrado no Sudeste do Brasil ResumoA cobertura do dossel tem efeitos significativos no ambiente do sub-bosque incluindo a disponibilidade de luz para o crescimento das plântulas. O objetivo do presente estudo foi verificar a heterogeneidade espacial e as mudanças sazonais da cobertura do dossel em uma area de Cerrado denso e sua relação com a radiação fotossintetica ativa diponivel no sub-bosque. Os valores do índice de área foliar (IAF) na estação chuvosa variaram de 0,9 a 4,83 com 40% dos valores dentro de 4,0 a 5,0, enquanto na estação seca o IAF variou de 0,74 a 3,3 com 53% dos valores dentro de 2,0 a 3,0. A luz abaixo do dossel (Qi) e razão de Lambert-Beer (Qi/Qo) foi obtida entre as 11:00 e 13:00 horas em dias ensolarados. Os valores também foram estatisticamente diferentes (p < 0.01) entre a estação seca e a chuvosa, com 72% dos pontos amostrados na estação chuvosa apresentando valores de densidade de fluxo de fotons fotossinteticamente ativos (DFFA) menores de 250 μmol.m -2 /s por volta do meio dia, enquanto na estação seca a maioria dos valores de DFFA variou entre 1500 a 1817 μmol.m -2 /s propiciando alta disponibilidade de luz para o sub-bosque. Na maior parte dos pontos amostrados, as plantas de sub-bosque não receberam quantidade de luz suficiente para 50% de sua capacidade fotossintetic...

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“…or shrub species (Brokaw 1985, Uhl et al 1988b, Tabarelli & Mantovani 1998, Nicotra et al 1999, Carvalho et al 2000, Denslow & Guzman 2000, Dickinson et al 2000. Other studies have examined all growth habits, but only in non-disturbed environments (Gentry & Dodson 1987, Galeano et al 1998.…”

Section: Height (M)mentioning

confidence: 99%

Community structure of vascular plants in treefall gaps and fire-disturbed habitats in the Atlantic rainforest, southern Bahia, Brazil

Martini¹,

Santos²,

Prado

et al. 2007

Rev. bras. Bot.

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-(Community structure of vascular plants in treefall gaps and fire-disturbed habitats in the Atlantic rainforest, southern Bahia, Brazil). The effects of disturbances on plant community structure in tropical forests have been widely investigated. However, a majority of these studies examined only woody species, principally trees, whereas the effects of disturbances on the whole assemblage of vascular plants remain largely unexplored. At the present study, all vascular plants < 5m tall were surveyed in four habitats: natural treefall gaps, burned forest, and their adjacent understorey. The burned area differed from the other habitats in terms of species composition. However, species richness and plant density did not differ between burned area and the adjacent understorey, which is in accordance to the succession model that predict a rapid recovery of species richness, but with a different species composition in areas under moderate disturbance. The treefall gaps and the two areas of understorey did not differ among themselves in terms of the number of individuals, number of species, nor in species composition. The absence of differences between the vegetation in treefall gaps and in understorey areas seems to be in agreement with the current idea that the species present in treefall gaps are directly related to the vegetation composition before gap formation. Only minimal differences were observed between the analyses that considered only tree species and those that considered all growth habits. This suggests that the same processes acting on tree species (the best studied group of plants in tropical forests) are also acting on the whole assemblage of vascular plants in these communities.Key words -atlantic forest, fire, growth habits, natural treefall gaps, species richness RESUMO -(Estrutura da comunidade de plantas vasculares em clareiras naturais e em área perturbada por fogo em uma floresta pluvial tropical Atlântica no Sul da Bahia, Brasil). Os efeitos das perturbações sobre parâmetros da estrutura de comunidade de plantas em florestas tropicais têm sido freqüentemente analisados. Porém, a maioria dos estudos realizados até o momento tem considerado somente plantas lenhosas, principalmente árvores, e o efeito de perturbações sobre toda a comunidade de plantas vasculares ainda não havia sido avaliado. No presente estudo, todas as plantas vasculares menores que 5 metros de altura foram amostradas em clareiras naturais, em uma área de floresta queimada em um incêndio acidental e em áreas de sub-bosque adjacentes. A área queimada diferiu das outras áreas em relação à composição de espécies, porém a riqueza de espécies e a densidade de indivíduos não foi diferente entre a área queimada e as áreas de sub-bosque. Estes resultados estão de acordo com os modelos sucessionais que prevêem que em locais sujeitos a perturbações de intensidade moderada ocorre uma rápida recuperação da riqueza de espécies, porém com uma composição de espécies diferenciada. As clareiras naturais e as áreas de sub-bosque não difer...

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Spatial Heterogeneity of Light and Woody Seedling Regeneration in Tropical Wet Forests

Cited by 309 publications

References 0 publications

A regeneração florestal em áreas de floresta secundária na Reserva Florestal do Morro Grande, Cotia, SP

A regeneração florestal em áreas de floresta secundária na Reserva Florestal do Morro Grande, Cotia, SP

Spatial and temporal variability of canopy cover and understory light in a Cerrado of Southern Brazil

Community structure of vascular plants in treefall gaps and fire-disturbed habitats in the Atlantic rainforest, southern Bahia, Brazil

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